The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Anatomical imaging is often performed prior to surgical procedures. MRI, CT or x-ray is often performed, for instance, before implantation of a prosthetic joint, such as a knee joint. The MRI, CT or x-ray image illustrates the joint, allowing doctors to study the joint prior to surgery. Furthermore, cut guides and/or anatomically matching instrumentation can be generated according to the images. As such, the components of the prosthetic device are more likely to be properly aligned, thereby improving comfort and performance for the patient, decreasing wear of the prosthetic components, and increasing longevity of the components.
In the case of a knee joint, it can be preferable for the reconstructed knee to fulfill a number of anatomical relationships. For instance, the mechanical axis of the leg, which extends from the center of the femoral head (i.e., the acetabulum head of the femur) to the center of the ankle, should pass through the middle of the knee joint. The axis of the femur should be inclined at a predetermined “valgus” angle (e.g., 7 degrees) with the mechanical axis of the leg. Furthermore, the axis of the tibia should be collinear with the mechanical axis of the leg. In addition, the mechanical axis of the leg, the axis of the femur, and the axis of the tibia should lie in a common plane when the leg is straightened. MRI, CT, x-ray or fluoroscopic imaging helps in analyzing the knee joint and to plan for surgery to repair the knee joint in order that the prosthesis achieves these and other relationships. More specifically, the MRI, CT, x-ray or fluoroscopic image can help in designing cut guides and planning other surgical procedures such that forces in the leg are transferred through the prosthetic components along the mechanical axis of the leg, from the center of the femoral head, through the middle of the knee joint, and to the ankle.
In the case of a knee joint prosthesis, an MRI, CT, x-ray or fluoroscopic image is often taken of multiple areas of the leg. More specifically, an MRI, CT or fluoroscopic image is taken of the knee joint where the prosthetic components will be implanted. Separate images may be generated for areas spaced away from the knee joint as well. For instance, images are generated for the hip and/or the ankle in order to obtain a more complete analysis of the leg and to locate the centers of the hip joint and ankle joint.
However, this type of imaging can take a long time and can be a complex process. Specifically, in the case of MRI, the patient is positioned in an MRI system, an MRI imaging coil is placed over the target area of the body, and the MRI image is taken of that target area. Then, the body is moved to align the next target area of the body with the MRI imaging coil, and another MRI image is taken. Thus, in the above examples, the knee, hip and ankle are imaged separately. Several MRIs may be necessary, and if the patient moves, the images may be degraded.